Conventionally, modular jacks having fundamental parts thereof standardized in conformance with the FCC standard or the like are used to connect telephone sets to telephone lines. The modular jack of this kind generally has a box-shaped housing with a plug inserting opening on the front surface of the housing. When the telephone set is connected to the telephone line, a plug which is provided on an end of the telephone line is inserted into the plug inserting opening. A plurality of contact pins are held in the housing so that one end of each of the contact pins projects from the bottom of the housing to constitute a terminal part and the other end of each of the contact pins projects within the plug inserting opening of the housing to constitute a contact part. The modular jack is placed on a printed circuit board which is secured to a main telephone body, in such a manner that the plug inserting opening is exposed to the outside of the telephone body. The terminal part constituted by the contact pins projecting from the bottom of the housing is soldered to respective circuit patterns on the printed circuit board within the telephone body.
Because of the dimensional variation of the jack caused by plastic shrinkage, the resultant position of the terminal part of a conventional modular jack is somewhat different from the nominal position as designed. For this reason, it is difficult and time-consuming to solder the terminal part of the modular jack to the printed circuit board. In addition, owing to the wicking strength induced in the contact area between the plastic housing and the contact pin, the flux migrates up along the contact pin to the contact part during fluxing and soldering processes so that the conductivity of the contact part is lowered. Furthermore, since sockets of conventional telephone sets are separate from the modular jacks where the sockets may be used as a DC power socket, antenna socket or an interface socket for another device, it is time-consuming to assemble the sockets and the modular jacks onto the telephone sets. Consequently, there is a need for practical and economical configurations of modular jacks which can overcome the disadvantages described above.